From f0ce0d3a331129309a46a6a9ac85fce35acae72b Mon Sep 17 00:00:00 2001 From: Pedro Alves Date: Thu, 23 Jul 2015 16:01:01 +0100 Subject: [PATCH] gdbserver: move_out_of_jump_pad_callback misses switching current thread While hacking on the fix for PR threads/18600 (Threads left stopped after fork+thread spawn), I once saw its test (fork-plus-threads.exp) FAIL against gdbserver because move_out_of_jump_pad_callback has a gdb_breakpoint_here call, and the caller isn't making sure the current thread points to the right thread. In the case I saw, the current thread pointed to the wrong process, so gdb_breakpoint_here returned the wrong answer. Unfortunately I didn't save logs. Still, seems obvious enough and it should fix a potential occasional racy FAIL. Tested on x86_64 Fedora 20. gdb/gdbserver/ChangeLog: 2015-08-06 Pedro Alves * linux-low.c (move_out_of_jump_pad_callback): Temporarily switch the current thread. --- gdb/gdbserver/ChangeLog | 5 +++++ gdb/gdbserver/linux-low.c | 7 +++++++ 2 files changed, 12 insertions(+) diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog index 79904d9bc05..fe31f731750 100644 --- a/gdb/gdbserver/ChangeLog +++ b/gdb/gdbserver/ChangeLog @@ -1,3 +1,8 @@ +2015-08-06 Pedro Alves + + * linux-low.c (move_out_of_jump_pad_callback): Temporarily switch + the current thread. + 2015-08-06 Pedro Alves * linux-low.c (linux_write_memory): Rewrite debug output to avoid diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c index 2146a2c3e76..792c1782b0e 100644 --- a/gdb/gdbserver/linux-low.c +++ b/gdb/gdbserver/linux-low.c @@ -3664,6 +3664,7 @@ static void move_out_of_jump_pad_callback (struct inferior_list_entry *entry) { struct thread_info *thread = (struct thread_info *) entry; + struct thread_info *saved_thread; struct lwp_info *lwp = get_thread_lwp (thread); int *wstat; @@ -3675,6 +3676,10 @@ move_out_of_jump_pad_callback (struct inferior_list_entry *entry) } gdb_assert (lwp->stopped); + /* For gdb_breakpoint_here. */ + saved_thread = current_thread; + current_thread = thread; + wstat = lwp->status_pending_p ? &lwp->status_pending : NULL; /* Allow debugging the jump pad, gdb_collect, etc. */ @@ -3702,6 +3707,8 @@ move_out_of_jump_pad_callback (struct inferior_list_entry *entry) } else lwp_suspended_inc (lwp); + + current_thread = saved_thread; } static int -- 2.30.2